CWE-122: Heap-based Buffer Overflow
Description
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
- Abstraction
- VariantA weakness tied to a specific language, technology or resource.
- Likelihood of exploit
- High
- Status
- Draft
Common consequences
- Availability
DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
Buffer overflows generally lead to crashes. Other attacks leading to lack of availability are possible, including putting the program into an infinite loop.
- IntegrityConfidentialityAvailabilityAccess Control
Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Modify Memory
Buffer overflows often can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. Besides important user data, heap-based overflows can be used to overwrite function pointers that may be living in memory, pointing it to the attacker's code. Even in applications...
- IntegrityConfidentialityAvailabilityAccess ControlOther
Execute Unauthorized Code or Commands; Bypass Protection Mechanism; Other
When the consequence is arbitrary code execution, this can often be used to subvert any other security service.
Potential mitigations
Pre-design: Use a language or compiler that performs automatic bounds checking.
- Architecture and Design
Use an abstraction library to abstract away risky APIs. Not a complete solution.
- OperationBuild and CompilationEnvironment HardeningEffectiveness: Defense in Depth
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
- OperationBuild and CompilationEnvironment HardeningEffectiveness: Defense in Depth
Run or compile the software using features or extensions that randomly arrange the positions of a program's executable and libraries in memory. Because this makes the addresses unpredictable, it can prevent an attacker from reliably jumping to exploitable code. Examples include Address Space Layout Randomization (ASLR) and Position-Independent Executables (PIE). Imported modules may be similarly realigned if their default memory addresses conflict with other modules, in a process known as rebasing (for Windows) and prelinking (for Linux) using randomly generated addresses. ASLR for libraries...
- Implementation
Implement and perform bounds checking on input.
- ImplementationLibraries or Frameworks
Do not use dangerous functions such as gets. Look for their safe equivalent, which checks for the boundary.
- Operation
Use OS-level preventative functionality. This is not a complete solution, but it provides some defense in depth.